Fluoride Uptake Research Articles

Potential role of Er:YAG laser and fluoride in the dental enamel remineralization: a Raman spectroscopy preliminary <i>ex vivo</i> study

Background and aims: Dental caries are a widespread oral disease and a serious public health problem, starting by teeth demineralization, which is a loss of minerals such as calcium and phosphate. Modern caries treatment is aimed at preventing the disease progression by teeth remineralization which is a supply of minerals to the enamel. The most popular remineralization method is the treatment of teeth with fluoride. Er:YAG laser has also gained research attention as a method for improving the uptake of fluoride and phosphate by introducing chemical and morphological changes into the structure of enamel but, while some researchers described it as effective, others found no significant effect from its application. This work aimed to further study the effect of Er:YAG laser, alone or combined with fluoride, to dental enamel. Materials and Methods: Twenty upper central human incisors, extracted for periodontal reasons, were used in the study. Samples were demineralized by acetic acid and divided into four groups: a) control, b) fluoride + Er:YAG laser, c) Er:YAG laser alone and d) fluoride alone. The remineralization rate of teeth was estimated by Raman Spectroscopy. Results: In comparison with the control group, the phosphate peak’s intensity increased notably for the teeth treated by fluoride, but decreased slightly for the teeth treated with Er:YAG laser and with a combination of the laser and fluoride. Conclusions: With the limits of this study, due to the limited samples number, Er:YAG laser, alone and combined with fluoride, seems to be not effective, at the parameters used, for the enamel remineralization.

Effect of the Addition of Varying Concentrations of Silver Nanoparticles on the Fluoride Uptake and Recharge of Glass Ionomer Cement.

This study aimed to compare the amount of fluoride uptake and the recharge and release characteristics of conventional glass ionomer cement (GIC) without any additives in comparison to conventional glass ionomer cement supplemented with silver nanoparticles (AgNPs) at two concentrations: 0.1% and 0.2% (w/w). A total of 60 specimens were used in this in vitro study. The sample was divided into six groups—including three groups without fluoride charge: Group 1 (conventional GIC), Group 2 (GIC with 0.1% silver nanoparticles), and Group 3 (GIC with 0.2% silver nanoparticles; and three groups with fluoride charge: Group 4 (conventional GIC with fluoride); Group 5 (GIC with 0.1% silver nanoparticles with fluoride); Group 6 (GIC with 0.2% silver nanoparticles with fluoride), where Group 1 is considered the control group and the other five groups are used as the test groups. The amount of fluoride released was measured on days 1, 2, 7, 15, and 30. The comparisons were made between the groups with and without fluoride and among all the groups. A significant difference in the amount of fluoride released was observed between the groups, with the highest amount occurring in Group 1, followed by Group 2; the lowest amount of fluoride released was observed in Group 3 (p < 0.05). The groups with fluoride recharge (Groups 4, 5, and 6) exhibited a higher amount of fluoride release than the groups with no recharge (Groups 1, 2, and 3); however, Group 1 has more fluoride release compared to all other groups on days 1, 2, 7, 15, and 30 (p < 0.05). The amount of released fluoride decreased from day 1 to day 30 in all of the groups in the study. Despite the antimicrobial and anticariogenic benefits of adding silver nanoparticles to GIC, it seems that fluoride release characteristics are significantly affected by the addition of this material. This may force the clinician to a compromise between the antimicrobial benefit of silver nanoparticles and the remineralizing advantage of fluoride.

Potential For Dietary Calcium to Prevent Fluoride Uptake in Children in Halaba Special District, Southern Ethiopia: Knowledge, Attitudes, and Practices of Mothers

Potential For Dietary Calcium to Prevent Fluoride Uptake in Children in Halaba Special District, Southern Ethiopia: Knowledge, Attitudes, and Practices of Mothers

Quantifying sodium [18F]fluoride uptake in abdominal aortic aneurysms

BackgroundAortic microcalcification activity is a recently described method of measuring aortic sodium [18F]fluoride uptake in the thoracic aorta on positron emission tomography. In this study, we aimed to compare and to modify this method for use within the infrarenal aorta of patients with abdominal aortic aneurysms.MethodsTwenty-five patients with abdominal aortic aneurysms underwent an sodium [18F]fluoride positron emission tomography and computed tomography scan. Maximum and mean tissue-to-background ratios (TBR) and abdominal aortic microcalcification activity were determined following application of a thresholding and variable radius method to correct for vertebral sodium [18F]fluoride signal spill-over and the nonlinear changes in aortic diameter, respectively. Agreement between the methods, and repeatability of these approaches were assessed.ResultsThe aortic microcalcification activity method was much quicker to perform than the TBR method (14 versus 40 min, p < 0.001). There was moderate-to-good agreement between TBR and aortic microcalcification activity measurements for maximum (interclass correlation co-efficient, 0.67) and mean (interclass correlation co-efficient, 0.88) values. These correlations sequentially improved with the application of thresholding (intraclass correlation coefficient 0.93, 95% confidence interval 0.89–0.95) and variable diameter (intraclass correlation coefficient 0.97, 95% confidence interval 0.94–0.99) techniques. The optimised method had good intra-observer (mean 1.57 ± 0.42, bias 0.08, co-efficient of repeatability 0.36 and limits of agreement − 0.43 to 0.43) and inter-observer (mean 1.57 ± 0.42, bias 0.08, co-efficient of repeatability 0.47 and limits of agreement − 0.53 to 0.53) repeatability.ConclusionsAortic microcalcification activity is a quick and simple method which demonstrates good intra-observer and inter-observer repeatabilities and provides measures of sodium [18F]fluoride uptake that are comparable to established methods.

Use of mining waste as a novel low-cost material for fluoride removal from groundwater in CKDu endemic areas of Sri Lanka

A cost-effective fluoride removal process from groundwater using locally sourced waste materials was postulated for use in remote areas such as northern Sri Lanka. The process is relatively simple to operate, reduces fluoride levels to meet WHO guidelines and uses locally available waste from lime extraction. The “Natural Red Earth” (NRE) waste was a mixture of clays (12.43 wt%) and iron oxides (8.13 wt%) deposited on quartz (64.04 wt%). The smallest mesh size (<63 μm) of NRE was preferred to remove fluoride due to enrichment with aluminium and iron materials. Fluoride exchange kinetics were relatively fast (ca. 5 min) for NRE which was ascribed to sorption sites present in an active coating. Equilibrium studies revealed a low fluoride loading (0.009 meq/g). Thermal modification of the NRE at 350 °C increased the maximum fluoride uptake to 0.014 meq/g. Exposure of NRE to 1 M hydrochloric acid solution was preferred as the fluoride sorption capacity was promoted to 0.02 meq/g. Protonated surface sites on NRE were considered responsible for the enhanced fluoride sorption capacity. Acid activated NRE successfully batch treated simulated groundwater contaminated with fluoride ions to meet WHO guidelines. Practically, NRE may be used in addition to a sand filter and charcoal bed if required to remove organic matter. The economics for constructing and using a new NRE based treatment system is suitable for rural farming communities in Sri Lanka.

Quantifying microcalcification activity in the thoracic aorta

BackgroundStandard methods for quantifying positron emission tomography (PET) uptake in the aorta are time consuming and may not reflect overall vessel activity. We describe aortic microcalcification activity (AMA), a novel method for quantifying 18F-sodium fluoride (18F-NaF) uptake in the thoracic aorta. MethodsTwenty patients underwent two hybrid 18F-NaF PET and computed tomography (CT) scans of the thoracic aorta less than three weeks apart. AMA, as well as maximum (TBRmax) and mean (TBRmean) tissue to background ratios, were calculated by two trained operators. Intra-observer repeatability, inter-observer repeatability and scan-rescan reproducibility were assessed. Each 18F-NaF quantification method was compared to validated cardiovascular risk scores. ResultsAortic microcalcification activity demonstrated excellent intra-observer (intraclass correlation coefficient 0.98) and inter-observer (intraclass correlation coefficient 0.97) repeatability with very good scan-rescan reproducibility (intraclass correlation coefficient 0.86) which were similar to previously described TBRmean and TBRmax methods. AMA analysis was much quicker to perform than standard TBR assessment (3.4min versus 15.1min, P<0.0001). AMA was correlated with Framingham stroke risk scores and Framingham risk score for hard cononary heart disease. ConclusionsAMA is a simple, rapid and reproducible method of quantifying global 18F-NaF uptake across the ascending aorta and aortic arch that correlates with cardiovascular risk scores.

Differential 18F–NaF uptake in various compartments in knee osteoarthritis: an observational study using PET/MRI

To investigate if the pattern of fluorine-18-labelled sodium fluoride (18F-NaF) uptake on integrated positron-emission tomography (PET)/magnetic resonance imaging (MRI) of bone marrow lesions (BML) and osteophytes differs between different knee compartments. Sixteen patients with no prior history of knee injury with or without pain were recruited for the study. The images of both knees were acquired on simultaneous PET/MRI. The acquisition was done after 45 minutes of intravenous injection of 18F-NaF 185-370 MBq (5-10 mCi) for 40 minutes. Each knee was divided into eight compartments patella, trochlea, medial central femur, lateral central femur, medial posterior femur, lateral posterior femur, medial tibia, lateral tibia, and cruciate ligament insertion specifically for BML. BML and osteophytes were scored using MRI Osteoarthritis Knee Score (MOAKS) criteria and their corresponding maximum standardised uptake values (SUVmax) recorded. BML and osteophytes both showed statistically significant differences among knee compartments, i.e., p-value <0.000 and<0.043 respectively. SUVmax for BML and osteophytes was greatest in the medial tibia. 18F-NaF PET/MRI showed that BML and osteophytes had differential uptake values due to bone remodelling amongst the various knee compartments and this may help to design disease-modifying osteoarthritis drugs in the future.

Adsorptive removal of fluoride using ionic liquid-functionalized chitosan – Equilibrium and mechanism studies

In this study, novel biosorbents, based on chitosan and imidazolium ionic liquid, were prepared for the removal of fluoride from aqueous solutions. The adsorbents were characterized by FTIR, SEM-EDS and low-temperature nitrogen adsorption-desorption. To investigate the adsorption mechanism and behavior of chitosan adsorbents, batch experiments were conducted under different adsorbent dosages (2, 4, 10 g/L), pH (4, 7, 9) and initial concentration (0.5–25.0 mg/L). The influence of the method of synthesis of ionic liquid on the adsorption performance were also studied. Experimental data were evaluated by Freundlich, Langmuir and Sips models. The introduction of ionic liquid significantly improved the uptake of fluoride compared to pure chitosan. The adsorption was influenced by the experimental conditions, as well as the method of ionic liquid synthesis. The highest fluoride removal was observed at pH 4 and found to decrease with increasing pH. The removal efficiency and adsorption capacity values indicated that the dose of 4 g/L was the optimum adsorbent dosage. The equilibrium data fitted best with the Sips isotherm and the maximum adsorption capacity reached 8.068 mg/g for modified chitosan beads. The mechanism of fluoride adsorption onto ionic liquid-modified chitosan involves electrostatic attraction, ion exchange and ion pair interaction.

Associations between coronary/aortic 18F-sodium fluoride uptake and pro-atherosclerosis factors in patients with multivessel coronary artery disease

Background18F-NaF PET/CT is a novel approach to detect and quantify microcalcification in atherosclerosis. We aimed to explore the underlying systematic vascular osteogenesis in the coronary artery and aorta in patients with multivessel coronary artery disease (CAD). MethodsPatients with multivessel CAD prospectively underwent 18F-NaF PET/CT. The coronary microcalcification activity (CMA) and aortic microcalcification activity (AMA) were calculated based on both the volume and intensity of 18F-NaF PET activity. Peri-coronary adipose tissue (PCAT) density was measured in adipose tissue surrounding the coronary arteries and the 18F-NaF tissue-to-blood ratio (TBR) was measured in the coronary arteries. Results100 patients with multivessel CAD were prospectively recruited. The CMA was significantly associated with the AMA (r = 0.70; P < .001). After multivariable adjustment, the CMA was associated with the AMA (Beta = 0.445 per SD increase; P < .001). The coronary TBR was also significantly associated with the PCAT density (r = 0.56; P < .001). The PCAT density was independently associated with the coronary TBR after adjusting confounding factors. ConclusionsCoronary 18F-NaF uptake was significantly associated with the PCAT density. There was a significant relationship between the coronary and the aortic 18F-NaF uptake. It might indicate an underlying systematic vascular osteogenesis in patients with multivessel CAD.

Respiration-averaged CT versus standard CT attenuation map for correction of 18F-sodium fluoride uptake in coronary atherosclerotic lesions on hybrid PET/CT

BackgroundTo evaluate the impact of respiratory-averaged computed tomography attenuation correction (RACTAC) compared to standard single-phase computed tomography attenuation correction (CTAC) map, on the quantitative measures of coronary atherosclerotic lesions of 18F-sodium fluoride (18F-NaF) uptake in hybrid positron emission tomography and computed tomography (PET/CT). MethodsThis study comprised 23 patients who underwent 18F-NaF coronary PET in a hybrid PET/CT system. All patients had a standard single-phase CTAC obtained during free-breathing and a 4D cine-CT scan. From the cine-CT acquisition, RACTAC maps were obtained by averaging all images acquired over 5 seconds. PET reconstructions using either CTAC or RACTAC were compared. The quantitative impact of employing RACTAC was assessed using maximum target-to-background (TBRMAX) and coronary microcalcification activity (CMA). Statistical differences were analyzed using reproducibility coefficients and Bland-Altman plots. ResultsIn 23 patients, we evaluated 34 coronary lesions using CTAC and RACTAC reconstructions. There was good agreement between CTAC and RACTAC for TBRMAX (median [Interquartile range]): CTAC = 1.65 [1.23 to 2.38], RACTAC = 1.63 [1.23 to 2.33], p = 0.55), with coefficient of reproducibility of 0.18, and CMA: CTAC = 0.10 [0 to 1.0], RACTAC = 0.15 [0 to 1.03], p = 0.55 with coefficient of reproducibility of 0.17 ConclusionRespiratory-averaged and standard single-phase attenuation correction maps provide similar and reproducible methods of quantifying coronary 18F-NaF uptake on PET/CT.

Evaluation Of Fluoride Uptake By Dentine Following Pretreatment With Silver Diamine Fluoride And Potassium Iodide Under Resin Modified Glass Ionomer Restoration Versus Resin Modified Glass Ionomer Restoration Alone In Carious Primary Molars: (In Vitro Study).

Evaluation Of Fluoride Uptake By Dentine Following Pretreatment With Silver Diamine Fluoride And Potassium Iodide Under Resin Modified Glass Ionomer Restoration Versus Resin Modified Glass Ionomer Restoration Alone In Carious Primary Molars: (In Vitro Study).

Cold plasma enamel surface treatment to increase fluoride varnish uptake

Among the available methods of enamel strengthening, fluoride varnish (FV) treatment has relatively better results. On the other hand, cold plasma technology has shown promising capacities in sterilizing the environment, surface modification, and improving adhesion. Accordingly, this study aimed to increase the adhesion of FV to the enamel surface to prolong the enamel interaction with FV with subsequently increased fluoride uptake by enamel. Emphasizing that the change in adhesion is evidence-based and has not been explicitly measured. For this purpose, we randomly divided twenty bovine teeth into two groups A (consisting of four teeth) and B (composed of four subgroups, each containing four teeth). Samples of group A and one specimen of each subset B investigated the effect of using Helium-DBD (He-DBDJ), Argon (ArJ), and Air-DBD jet on the enamel surface. Other B specimens are devoted to studying the release of FV fluoride ions from processed enamel. Two diagnostic techniques, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), have been utilized to examine the samples' surface morphology and chemical analysis, respectively. Finally, the release of fluoride ions into distilled water was measured by an ion-selective electrode (ISE). SEM images showed that ArJ and Air-DBD significantly damaged enamel hexagonal structures, whereas, in the case of He-DBDJ, the hexagonal structures have only altered from convex to concave. EDX indicated an increase in calcium to phosphorus ratio and the amount of fluoride and sodium uptake on the enamel surface layer in the group processed with He-DBDJ plasma. The latter helps restore the damaged parts of the enamel. Analysis of fluoride released from the FV did not show a significant change owing to plasma processing (P ≤ 0.112). The combination of cold plasma and fluoride varnish treatment on the enamel surface might be considered as a more promising approach to increasing enamel resistance to tooth decay.

Natural water defluoridation by adsorption on Laponite clay.

Safe drinking water is a necessity for every human being, but clean water is scarce and not easily available due to natural geochemical factors or industrial pollutant activity. Many issues involving water quality could be greatly improved using clays as adsorbents. We highlight for the first time, the uptake of fluoride from natural water by Laponite, synthetic hectorite clay, in raw and modified state. A series of batch adsorption experiments were carried out to evaluate the adsorption potential of the different parameters. The optimized parameters were: contact time, adsorbent dose and pH. It was found that fluoride uptake from natural water was better using raw Laponite and inorganic-modified Laponite than using organic-modified Laponite clays. Adsorbents were characterized before and after fluoride adsorption by X-ray diffraction, X-ray fluorescence, FTIR, thermo gravimetric analyses and 19F solid state NMR spectroscopy. The experimental data showed that both Langmuir and Freundlich models fitted an adsorption isotherm well. Thermodynamic parameters such as Gibbs free energy (ΔG°), enthalpy (ΔH°), and entropy (ΔS°) were calculated. These parameters indicated that fluoride adsorption onto Laponite was nonspontaneous and endothermic in temperature range between 25 and 45 °C.

Ultrasound-Assisted facile synthesis of Ce/Fe nanoparticles impregnated activated carbon for fluoride remediation

Fluoride contamination is a severe problem affecting the safety of drinking water around the world. The study focused on the facile synthesis of activated carbon (AC) impregnated with cerium and iron via ultrasonication and performance evaluation of these novel adsorbents using sono-sorption for defluoridation of drinking water. The use of ultrasound demonstrated maximum removal efficiency of 95.4% just after 20 min compared to shaker, where only 87% fluoride was removed after 60 min using AC having Ce/Fe molar ratios of 2:1 (AC/Ce/Fe–1). The key finding which makes our study outstanding is the rapid increase in adsorption rate upon application of ultrasonication while improving the adsorption capacity. The kinetics data obtained was best fitted with the pseudo-second-order model. The maximum adsorption capacity of AC/Ce/Fe–1 was obtained as 52.3 mg/g at room temperature and the synthesized material maintained its relatively high fluoride uptake up to the fourth cycle. The material shows the highest adsorption capacity as compared to the metal-modified AC available in the literature, making it ideal for fluoride removal from drinking water.

Effectiveness of Nanoparticle-Based Acidulated Phosphate Fluoride (APF) Gel on Surface Enamel Fluoride Uptake: an Interventional Study.

Statement of the Problem: Despite topical fluoride being used for over 50 years in caries prevention, its complete potential in terms of formation of fluorapatite enamel and prolonged surface retention has not been harnessed.Purpose: This study aimed to assess the effectiveness of nanoparticle based acidulated phosphate fluoride (APF) gel on surface enamel fluoride uptake through split mouth design over a period of six months, on patients undergoing orthodontic treatment and indicated for bilateral extraction of premolars on at least one of the arch.Materials and Method: A split mouth non randomized clinical trial was performed. Each of the 30 participants received one application of 4 minutes duration of both the intervention: Right half of the mouth received nanoparticle based APF gel, and left half of the mouth received conventional APF gel (16 Oz Pascal Corp.; strawberry flavor). Bilateral acid etch biopsy of enamel surface was take at 3 intervals- baseline,24 hours and 30 days. Using 1ml of 0.5M perchloric acid, acid etch enamel biopsy was taken for all the study subjects at 3 intervals of time (baseline, 24 hours and 30 days), bilaterally on the buccal and palatal/lingual surface of maxillary or mandibular premolars indicated for extraction, using 1 (l of 0.5M perchloric acid. After the premolars were extracted, scanning electron microscope (SEM) analysis was done to determine the surface characteristics of enamel in both groups.Results: Overall, both fluoride uptake and depth of biopsy remained significant even after controlling for the covariates (time, group) individually and simultaneously (p< 0.05). Further analysis showed that fluoride uptake was significantly increased and biopsy depth significantly decreased in the nanoparticle based APF gel group at 24 hour and 30 day evaluation respectively.Conclusion: By reducing the size of sodium fluoride to increase the surface enamel uptake, our results support the use of this top down approach as a promising strategy for effective delivery of topical fluorides. This highlights that the top down approach of nanoscience to reduce the size active compound sodium fluoride has increased the uptake and retention of surface enamel fluoride.

Fluoride tolerance in rice is negatively regulated by the 'stress-phytohormone' abscisic acid (ABA), but promoted by ABA-antagonist growth regulators, melatonin, and gibberellic acid.

The present manuscript aimed at investigating whether abscisic acid (ABA) promotes fluoride tolerance, similar to inciting salt adaptation in rice. Seeds of three salt-tolerant rice genotypes were maintained at 32°C under 16/8h light/dark photoperiodic cycle with 700μmol photons m-2s-1 intensity and 50% relative humidity in a plant growth chamber for 20days. Suppressed ABA biosynthesis, and downregulated expression of ABA-inducible genes like Rab16A, Osem, and TRAB1 triggered NaCl-induced growth inhibition and physiological injuries like chlorophyll degradation, electrolyte leakage, formation of H2O2, malondialdehyde, and methylglyoxal in Matla. Reduced ABA accumulation increased the levels of melatonin and gibberellic acid in NaF (50mgL-1)-stressed Nonabokra and Matla, which altogether promoted fluoride tolerance. Higher ABA content in NaF-stressed Jarava stimulated fluoride uptake via chloride channels, thus exhibiting severe fluoride susceptibility, in spite of higher production of ABA-associated osmolytes like proline, glycine-betaine and polyamines via the concerted action of genes like PDH, ADC, ODC, SAMDC, SPDS, SPMS, DAO, and PAO. Increased accumulation of compatible solutes in presence of high endogenous ABA promoted salt tolerance in Jarava; the same was insufficient to ameliorate fluoride-induced injuries in this cultivar. Treatment with ABA biosynthetic inhibitor, Na2WO4 promoted fluoride tolerance in Jarava, whereas further supplementation with exogenous ABA resulted in reversion back to fluoride-susceptible phenotype. Our work clearly established that ABA cannot always be considered as a 'universal' stress hormone as known in literature, since it acts as a negative regulator of fluoride tolerance which is more tightly regulated in rice via melatonin- and gibberellic acid-dependent pathways in ABA-independent manner.

Mechanisms of fluoride uptake by surface-modified calcite: A 19F solid-state NMR and TEM study

Fluoride pollution in groundwater is a serious problem threatening millions of people worldwide. Calcite is considered an ideal adsorbent for defluoridation owing to its widespread presence and low cost. To further enhance its performance, we synthesize a series of phosphate-modified calcites with varying phosphate concentrations. The surface modification led to the formation of a nanosized hydroxyapatite (HAP) coating on the calcite surface. With increasing concentrations of phosphate used for modification, the BET specific surface area of the adsorbents was dramatically enhanced, resulting in a great enhancement of F uptake. At low F concentrations (i.e., <1 mM), surface-modified calcite can achieve up to 25 times higher F removal efficiency than calcite. The 19F solid-state MAS NMR spectra yielded three distint peaks at δ(19F) = −86 ppm, −99 ppm, and −122 ppm, representing the formation of carbonate fluorapatite (CFA), fluorapatite (FAP), and coprecipitated F, respectively. This provides strong evidence for the contribution of newly formed HAP to F removal. In contrast, at high F concentrations (e.g., >2 mM), surface modification did not enhance F uptake by calcite. The 19F solid-state MAS NMR analysis revealed that the predominant deflurodation mechanism is the formation of CaF2 precipitates (δ(19F) = −108 ppm) for both pristine and modified calcite at high F concentrations. Under this condition, the contribution of the newly formed nanosized HAP to F uptake is insignificant. Taken together, our results demonstrated the potential of surface modification of calcite as a cost-effective technique for defluoridation for most F-rich groudwater.

Insight into biosorptive uptake of fluoride by chemically activated biochar: experimental modeling and parametric optimization

Insight into biosorptive uptake of fluoride by chemically activated biochar: experimental modeling and parametric optimization

Adsorption of Fluoride from Water Using Aluminum Coated Sand: Kinetics, Equilibrium, Effect of pH, and Coexisting Ions

An aluminum coated sand (AlCS) was evaluated as a metal oxide adsorbent for adsorption and removal of fluoride from water using a low-cost adsorbent with potential application in continuous flow adsorber systems. Surface characterization of the AlCS sorbent was performed using TEM, SEM/EDX, XRD and BET. The AlCS sorbent contained mostly amorphous aluminum oxides based on adsorbent characterization results. Favorable adsorption of fluoride onto the AlCS sorbent occurred according to the Langmuir and Freundlich adsorption equations, while physical adsorption of fluoride onto the AlCS sorbent was observed based on results from the Dubinin-Radushkevich equation. Fluoride adsorption onto the AlCS sorbent followed pseudo-second order kinetics, while surface charge analysis indicated a pHPZC of 7.1 for the AlCS sorbent. Effective fluoride removal occurred over a broad pH range from 3 to 11 with a maximum fluoride removal observed at pH 4 to 5. The effect of co-existing ions in water resulted in a decrease in fluoride uptake in the presence of bicarbonate, while resulting in an increase in fluoride uptake in the presence of calcium. The AlCS sorbent was a low-cost and sustainable adsorbent for effective adsorption and rapid removal of fluoride from water within an hour.

Effect of dentifrices with different pH and fluoride concentrations on fluoride levels in biofilm and nails: an RCT.

to evaluate the effect of dentifrice pH and fluoride concentration ([F]) on fluoride uptake on the biofilm and nails of children from a non-fluoridated area. two hundred and twenty-eight two- to four-year-old children were randomly allocated into 3 groups according to the type of dentifrice: G1: 1100 μg F/g, pH 4.5 (n = 76); G2: 750 μg F/g, pH 4.5 (n = 74); and G3: 1100 μg F/g, pH 7.0 (n = 78). Nails were collected at 4, 8, and 12 months after starting dentifrice use and biofilm was collected 5 and 60 minutes after toothbrushing. The concentrations of F in nails and biofilm were analyzed by HMDS facilitated diffusion. Data were analyzed by Kruskal-Wallis/Mann-Whitney's test and the comparison between biofilm collection times was done using Wilcoxon test (p £ 0.05). a significant reduction of [F] in biofilm was observed 60 minutes after toothbrushing, regardless of the dentifrice used. However, 5 minutes after toothbrushing, G1 had a significantly higher [F] compared to G2 and G3, and 60 minutes after toothbrushing, [F] was significantly higher for G1 and G2 compared to G3. G1 and G3 had significantly higher [F] in the nails compared to G2. a lower dentifrice concentration is a relevant factor for the reduction of excessive fluoride intake. The use of a low-F acidified dentifrice combines the reduction of fluoride uptake with caries prevention by leading to greater incorporation of F into the biofilm over time.